3-Dimensional camera

ABSTRACT

This invention relates to a reflex camera device having a single lens for the photography of right and left images from an object space transmitted as first and second light ray bundles from two positions separated by an interocular distance onto a single frame of a single film strip; a first set of mutually extinguishing filters such as polarizers, one filter of the set along each of the first and second light ray bundles; a single frame aperture; a second set of mutually extinguishing filters near the image plane to separate the first and second light ray bundles from each position respectively into right and left adjacent images onto the single frame; means to control convergence, focus and interocular distance; and a reflex viewer containing a third set of mutually extingusihing filters to enable the simultaneous viewing and photographing of right and left adjacent images. SU 
     This invention relates to a reflex camera device for 3-dimensional photography. With this device, right and left light ray bundles from the object space being photographed carry the right and left images, respectively, to two positions, separated by an interocular distance, and these images are placed on adjacent areas of a frame of a film strip. Means are provided to control convergence, focus and interocular distance. A reflex viewfinder enables the simultaneous viewing and photographing of the right and left images. 
     BACKGROUND OF THE DISCLOSURE 
     The prior art shows many devices for photographing images from two positions separated by an interocular distance to form right and left adjacent images onto a frame of a film strip, one above the other or side by side; or two cameras for photographing right and left images from two positions separated by an interocular distance onto two film strips; subsequently the corresponding right and left images on frames from these two film strips were combined by uniform or anamorphic reduction to form right and left adjacent images side by side or one over the other on a single frame of a single film strip. In the former, mechanical devices such as rotating mirrors or shutters with reflecting or prism beam splitters, or a double lens system was used. These former devices were complex, lacked control of essential variables, or were limited in angular aperture. In the latter, the process of of combining two film strips onto a single film strip was costly because of the use of two film strips, and the precision registration and reduction techniques required. These difficulties inhibited the production of 3-dimensional motion pictures. 
     The present invention overcomes the difficulties of the prior art by a device which uses a conventional single strip motion picture camera with a single lens, and which provides a wide angle aperture, adjustable convergence and focal length. The device of the present invention contains no mechanical moving parts except the conventional camera shutter mechanism and controls. The device comprises relatively simple and inexpensive optical elements in a compact unit attached to a standard monocular camera, preferably of the reflex type, to enable the scene to be photographed while simultaneously presenting the right and left adjacent images to the cameraman, so that the convergence and focal length may be adjusted as required. 
     It is an object of this invention to provide a simple inexpensive optical device to adapt a monocular motion picture camera for the photography of 3-dimensional motion pictures. 
     It is an object of this invention to employ a single lens with mutually extinguishing pairs of filters before and after the lens to image right and left adjacent images on a single frame of the film at the gate, and at a reflex viewfinder. 
     It is an object of this invention to provide an optical device for adapting a monocular motion picture camera for the photography of 3-dimensional motion pictures in which the convergence, focus, and interocular distance is controlled simultaneously or independently while the scene being photographed is viewed by the cameraman through a reflex viewfinder. 
     It is an object of this invention to provide a compact optical device which has no moving mechanical parts other than the angular or distance adjustments of its optical elements for photographing right and left adjacent images onto a single frame of a single strip film. 
     It is also an object of this invention to provide a binocular viewer or viewfinder to fuse adjacent stereo image pairs into a 3-D image in a viewing device. 
     Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. These drawings show, for illustrative purposes only, preferred forms and techniques of the invention:

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows diagrammatically an isometric exploded view of the3-dimensional camera device according to this invention.

FIG. 2 is a plan view section through an optical device according tothis invention.

FIG. 3 is a diagrammatic side view vertical section through the opticalelements of the present invention.

FIG. 4 is a drawing of polarized filter elements utilized in the gateand viewfinder of the camera.

FIG. 5 shows an electromechanical system for controlling convergence andfocus independently or simultaneously.

FIG. 6 shows the right and left images as they appear in the film gateand image plane of the viewfinder.

FIG. 7 shows a diagrammatic plan view of a reflex motion picture cameramodified according to this invention, and provided with a binocular 3-Dviewfinder.

Referring now to FIg. 1, there is shown an isometric exploded view ofthe 3-dimensional camera device according to this invention. In thisFigure, the optical elements, principal rays and major adjustments arediagrammatically shown. Only the necessary conventional camera elementsare shown in this view. The camera employed may be of the reflex type,such as the Arriflex 35mm camera which is often employed in professionalmotion picture photography. This camera has a revolving 45° conicalshutter element 1, the front solid surfaces of which are reflecting. Thestereo image rays are deflected at F in the direction FG normal to the ZZ' axis toward the viewing device. The image photographed at the gateplate 2 onto the film strip 3 is also projected identically into theviewfinder 4. The shutter 1 occludes the film gate 2 while the filmstrip 3 is being drawn down to the next frame by a mechanism not shown.Light from the scene being photographed proceeds along horizontal axes LL' and R R', which are in the same plane and converge to a point O inspace at a distance p, as shown in FIG. 5. The angle between axes L L'and R R' is θ. The right and left adjacent image pairs are seen fused inthe viewfinder 4, shown in FIG. 7, exactly as they will appear whenprojected on a screen in 3-D.

By a deflector is meant an optical element when reflects a ray by amirror, total internal reflecting prism, or a half-silvered reflectingplane. By vertical is meant the Y axis; by horizontal, the X axis; the Zaxis is the optical axis Z Z' of the camera lens 6. Axes X, Y, and Z arenormal to each other. Z₁ Z₁ ' is the first optical axis of the upper orfirst image in the gate which passes through its optical center and theoptical center 5 of the lens 6. Z₂ Z₂ ' is the second optical axis ofthe lower or second image in the gate which passes through its opticalcenter and the optical center 5 of the lens 6. A solid glass elementrather than a mirror and air path is used to decrease the angulardivergence of the ray bundles, enabling a closer packing of theelements, enabling a standard interocular distance a of about 67mm to bemaintained.

By a polarizing axis is meant that direction of the filter parallel tothe transmitted electric vector of light, which is known crystallinepolymeric polarizers is parallel to the stretch axis of the polarizingmaterial.

In FIG. 1, there is shown for horizontally deflecting the right stereoimage light ray bundles along R R' to pass along the first optical axisZ₁ Z₁ ', a first fixed horizontal deflector 7, and a second horizontalrotatable deflector 8, having a vertical axis Y₁ Y₁ '. There is alsoshown a first vertical deflector 9 and a second vertical deflector 10,which may be total internal reflecting 45° prisms or mirrors tovertically deflect the left stereo image light ray bundles along L L' topass along the second optical axis Z₂ Z₂ '.

The light ray bundles of the right and left images coverge to theoptical center of the lens through an angle determined by the field ofview of the lens. For example, in a 50mm lens, the field of view if 24°horizontally and about 12° vertically. With glass elements thisdivergence is decreased by a factor of n, the index of refraction of theglass. Thus, the horizontal divergence of these light ray bundles inglass, in the horizontal plane, is ˜18°, or 9° on each side of thecentral axis of the light ray bundles. The vertical divergence of theselight ray bundles in glass is ˜8°, or 4° above and below the axis of thelight ray bundles. To accommodate this converging light ray bundlethrough the first horizontal deflector 7, the ray CD diverges from theray BE'. To enable convergence to near or far images, a set ofachromatic prisms 11 and 12 is provided. These achromatic prisms have adeviation of about 5° each, or a total of about 10°.

To provide convergence control, for example, from ∞ to 1 meter, theadjustment of the angle θ between the optical axes R R' and L L' of theright and left images if from 0° to about 4°. A rotation of the secondhorizontal deflector 8 by α degrees changes the reflected ray DE by 2α,and changes the direction of the ray CD by 2(2α)= 4α at the firsthorizontal deflector 7. As the second horizontal deflector 8 is rotated1° around the vertical axis Y₁ Y₁ ' by the worm gear 13 and the worm 14,the convergence angle θ changes 4°. The deflector 8 may have variousforms. In one embodiment it is a cube with a half-silvered diagonalplane convering the entire lens aperture. In a second embodiment, it isa totally reflecting prism across only the half plane below the opticalaxis Z Z' of the lens 6, and a fixed or rotatable solid cube occupiesthe half plane above the optical axis Z Z'.

The left and right ray bundles diverge from a point O in the objectspace which is at a distance p from the optical center 5 of the lens 6.Simultaneously, as the convergence angle θ is changed, the change in thedistance p is accomplished by rotating the lens worm gear 13 and worm14. The worm gear 13 rotates the lens 6 and moves it back and forthalong its axis Z Z' to focus the image at the plane of the gate 2. Thefilm 3 passes the gate 2, which is divided into two areas, an upperimage in a first area 16 for the right image, and a lower image in asecond area 17 for the left image. The right and left, upper and lowerimages 16 and 17, respectively, are separated by a dark bar 18. The darkbar 18 provides a sharp upper and lower border to the projected imagesupon the screen, as described in related application, Ser. No. 329,733,filed Feb. 5, 1973. The shutter 1, shown in cutaway section, has areflecting surface which deflects the image along a path FG towardmutually extinguishing filters 19 shown in FIG. 6 at the diffusionscreen 15 at the image plane of the viewfinder 4 shown in FIG. 7.

Referring to FIG. 6, the mutually extinguishing filters 19 have upperand lower areas 20 and 21, respectively, separated by the dark bar 22.Horizontal cross hairs 23 and 24 bisect the areas 20 and 21respectively. Vertical cross hairs 25, 26, etc. extend across the areas20 and 21. The horizontal displacement Δ between a right inverted imageR of point O and left inverted image L of point O on areas 20 and 21respectively may be calibrated against the convergence angle θ; forexample at Δ₁ = O, θ = O and the convergence distance p = ∞; at Δ₁ =5mm, θ= 4°, and the convergence distance p = 1 meter. The horizontalcross hairs 23 and 24 are used to vertically align the right and leftimages at infinity and to thus establish a fixed reference distanceseparating the upper and lower images. If a constant distance is notmaintained between the upper and lower, right and left imagesrespectively, then these distances must be adjusted during the printingof the film. This difficult and costly procedure is eliminated by thepresent invention.

Referring now to FIGS. 2 and 3, the path of the light ray bundles of theright and left images are now traced. The light ray bundles of the rightimage proceed along the axis R R' through the first convergingachromatic prism 11, being reflected at D by the first horizontaldeflector 7 along the path DE, whence the rays are reflected by thesecond horizontal rotatable deflector 8 along the path EF, passingupward through the optical center 5 of the lens 6, to the upper area 16at the gate 2. The light ray bundles of the left image pass along axis LL' through the second converging achromatic prism 12 toward the firstvertical deflector 9, are reflected at A vertically along path AB, andare reflected again by the second vertical deflector 10, along the lineBC; then downward through the optical center 5 of the lens 6 to thelower area 17 of the gate 2.

The path BC passes through the glass block 27, which may be an extensionof the second horizontal deflector 8. To provide vertical adjustment ofthe right and left stereo images at the film gate 2 and the focal planeof the viewfinder 4, the second vertical deflector 10 may be rotatedthrough a few degrees about the X₁ X₁ ' axis. When the appropriatevertical separation of the right and left images is achieved, thisposition is locked. The first and second vertical deflectors 9 and 10displace and rotate the light ray bundles from the axis L L',respectively, by a vertical distance D₂, and an angle γ, toward thesecond image are 17, along the second optical axis Z₂ Z₂ '.

The first set of mutually extinguishing filters 19 comprises a rightpolarizing filter 28 and a left polarizing filter 29, which may, forexample, have a vertical polarizing axis; and a horizontal polarizingaxis, respectively; shown mounted and laminated to faces of the rotablesecond horizontal deflector 8 and the glass block 27.

FIG. 4 shows the second set of mutually extinguishing filters 30 whichcomprise polarizing filters 31 and 32 with a dark bar separator strip 18between them, laminated between or on glass or plastic and mounted inproximity to the film strip 3 at the gate 2. The filter set comprises anupper polarizing filter 31 in area 16, polarized with its axis ofpolarization vertical, and the lower polarizing filter 32 in area 17 ispolarized with its axis of polarization horizontal.

The camera lens 6 focuses the object at intersection point O onto theplane of the film 3 at the gate 2. The lens position along its opticalaxis Z Z' is controlled in the usual manner by rotating the lens barrel,using a worm gear 33 turned by the worm 34 on shaft 35. The convergenceangle θ of the right and left optical axis R R' and L L' respectively totheir intersection point O varies from 0° to 4°, controlled by arotation of the second horizontal deflector around the Y₁ Y₁ ' axis,which passes vertically through its diagonal plane. The deflector 8 ismounted on the shaft of the worm gear 13, which also has Y₁ Y₁ ' as itsaxis. The convergence control shaft 36 rotates the worm 14, worm gear 13and deflector 8. To automatically coordinate convergence and focus, theshafts 35 and 36 may be mechanically interlocked. Light ray bundlescarrying both the right and left images are mixed and pass through thesame lens 6 which is a common channel for these rays. These mixed lightrays are distinguished and separated into the right and left adjacentimages on a single frame of the film 3 by the first and second sets ofmutually extinguishing polarizing filters.

Thus, the ray bundle carrying the right image is polarized vertically bypolarizing filter 28 and is extinguished by the lower horizontallypolarizing filter 32 at the lower area 17 of the film gate 2, and isadmitted by the upper vertically polarizing filter 31 at the upper area16 of the film gate 2; and the ray bundle carrying the left image ispolarized horizontally by the polarizing filter 29, and is extinguishedby the upper vertically polarizing filter 31 at the upper area 16 of thefilm gate 2, and admitted by the lower horizontally polarizing filter 32at the lower area 17 of the film gate 2. The right and left images thusappear only in the appropriate areas 16 and 17 on the film strip 3 aboveand below the central dark bar separator strip 18.

The angular adjustments of the second horizontal deflector 8 around thevertical axis Y₁ Y₁ ' and of the second vertical deflector 10 around thehorizontal axis X₁ X₁ ', respectively, enable the right and left imagesto be centered in their respective positions at the gate and at theviewfinder. The angular adjustment of second horizontal deflector 8controls the convergence angle θ of the light ray bundles carrying theright and left images.

Referring to FIG. 5, shafts 35 and 36 are provided with the externalcalibrated dials 37 and 38, respectively. To vary the divergence of theright and left images, the second deflector 8 is turned through an angleα from 0° to about 1°, by the worm gear 13, which may have for example360 teeth. A single turn of the shaft 36 then causes the deflector 8 toturn through an angle of 1°. The dial 38 may be calibrated in 100divisions, of 0.01° per division. Assuming that, for an object O frominfinity to 1 meter from the lens center 5 the lens worm gear 33requires a rotation of 45° to vary the distance q from the lens centerto the image plane 2 on the film strip 3; then one turn of the shaft 35rotates gear 33 by 45°, or 1/8 turn. In this case, the gear combination33, 34 may comprise sprial gears with an 8:1 ratio.

A motor 39 drives the gear box 40 and shafts 35 and 36 through theclutches 41 and 42, respectively. The motor/gear box 39, 40 may be anintegral assembly, powered via electric leads 43, and its speed bycontrol dial 44 via a conventional speed control electric circuit 45.This drive and clutch mechanism allows the coupling or independentcontrol of the convergence angle θ of the axes L L' and R R' and thefocus onto the object O at a distance p from the optical center 5 of thelens 6. When the clutches are engaged, the difference angle Δα and thedifference distance Δq of the optical center 5 of the lens 6 to the filmplane 3 are coupled, and Δq is proportional to Δα.

To control tracking toward or away from the camera of the convergenceand focus, the motor 39 may be reversed by the speed control dial 44.The clutches 41 and 42 may be disengaged and the dials 37 and 38 set toindependently focus and coverge. For example, by rotating the secondhorizontal deflector 8, the image axes may be converged upon a near orfar object. The focus may be independently adjusted near or far. If itis required to simultaneously converge and focus upon an object, and ifthe object is moving toward or away from the camera, the focus andconvergence may simultaneously track either rapidly or slowly byengaging the clutches 41 and 42, setting the dial 44 for positive ornegative tracking speed (object moving toward or away from the camera)depending upon the motion of the object relative to the camera; and thedial 47 for the distance p of the object to the camera which controlsthe shaft angle differential 46. Push button control 48 actuates thetracking. The cameraman simultaneously observes the right and leftimages at the diffusion screen 15, using a monocular eyepiece on theviewfinder, such as 53, without prism or polarizer. The images then areseen one over the other just as they will appear on the film.Alternatively, utilizing the two binocular eyepieces 53 and 54, theimage is seen in 3-D as herein described in connection with FIG. 7. Thecameraman is thus able to automatically track or independently controlthe focus and convergence.

When there is little or no vertical parallex, all objects on the samelevel will appear on the same horizontal line. With vertical parallax,left and right images of far and near objects may be alignedhorizontally on one image, but the same objects will appear verticallydisplaced on the other image. For a satisfactory 3-D presentation, thiscondition cannot be tolerated if the vertical parallax exceeds a fewpercent of the picture height. If the vertical deflection D₂ and angle γare not correctly adjusted, a vertical parallax of near and far imageswill be observed. Vertical and angular adjustments D₂ and γ,respectively, may be provided on the first and/or second verticaldeflectors, to adjust the vertical deflection distance D₂ and directionof the left image light ray bundles into a path along the second opticalaxis Z₂ Z₂ '.

SYMBOLS

a = interocular distance

b = width of bar separator

d = differential

f = focal length of lens

h = height of stereo image

k, k₁, k₂, k₃ = constants

n = index of refraction of the glass elements

p = distance of the object to the optical center of the lens

p_(o) = initial distance of object to center of camera lens

q = distance from optical center of lens to plane of film

rpm = revolutions per minute

t = time

w = frame width of stereo image

z_(o) = distance between the optical center and vertical deflection pathAB

D₁ = distance between centers of upper and lower images

D₂ = ab, the vertical deflection distance

H = standard frame height

K = 4f² /a

V = velocity of approach or recession of object from camera

W = standard frame width

α = angle by which reflecting plane of deflector differs from 45°position of that plane relative to X axis

β = angle through which lens worm gear is turned

γ = angle between axes Z₁ Z₁ ' and Z₂ Z₂ '

Δ₁ = horizontal displacement between a corresponding point on right andleft images

θ = convergence angle between intersection of optical axes L L' and R R'

ω_(c) = angular velocity of convergence shaft

ω_(f) = angular velocity of focus shaft

Δ = difference

MATHEMATICAL OPTICS SECTION

For a simple lens system:

    1/f = 1/p+1/q                                              (1)

Solving for a distance between a film plane and the optical center, q:

    q = fp/(p-f)                                               (2)

Differentiating:

    (dq/dp) = -f.sup.2 /(p-f).sup.2                            (3)

Since usually, p >> f:

    dq ≈ -(f/p).sup.2 .sup.. dp                        (4)

For small θ, the relationship between the distance of the object to theoptical center of the lens p and the interocular distance a is:

    p ≈ a/θ                                      (5)

Differentiating:

    dp = (-a/θ.sup.2)dθ                            (6)

From (4), (5), and (6):

    dp = -(fθ/a).sup.2 (-a/θ.sup.2) d θ      (7)

which reduces to:

    Δq = (f.sup.2 /a)Δθ                      (8)

The relationship between the change in the angle of the secondhorizontal deflector Δα and the change in the angle Δθ between theoptical axes of the right and left images is:

    Δθ = 4 Δα                          (9)

From (8) and (9):

    Δq = (4f.sup.2 /a)Δα = K Δα  (10)

the change in Δq is usually accomplished by turning the barrel of thelens 6 through an angle Δβ. The barrel is threaded into the lensmounting which axially shifts the lens a distance Δq for a change ofbarrel angle Δβ. That is

    Δβ = kΔq                                  (11)

From (10) and (11):

    Δβ= k KΔα=k.sub.1 Δα    (12)

Equation (12) shows that the angle Δαthrough which the second horizontaldeflector 8 is rotated to adjust the convergence is directlyproportional to Δβ, the angle through which the lens worm gear 33 isturned to obtain a sharp image on the film plane at the gate 2.

For an interocular distance fixed at a = 67mm, the average constantdistance between the right and left human eyes, the constant term K =4f² /a is about 38 for a 25mm lens, 150 for a 50mm lens, and 300 for a70mm lens.

The angle θ between the optical axes of the right and left lenses variesfrom zero at p = ∞ to about 4° at p = 1mm, usually the closest workingdistance to a camera. Consequently Δα varies from zero to ∞1°.

EXAMPLE 1

Given: A lens of focal length f = 50mm, the interocular distance a =67mm, and θ set initially at 0, with the object distance p = ∞.

The object distance is changed to p = 1mm, or 10³ mm, by rotating thesecond horizontal deflector 8 through an angle Δα.

Find:

1. Δθ

2. Δα

3. Δq

Solution:

From (5):

    θ = a/p=67/10.sup.3 radians = 6.7 × 10.sup.-.sup.2 . (180/π)°

    θ= 3.8°

    Δθ= 3.8 = 0 = 3.8°                      Ans. (1)

From (9):

    Δα = Δθ/4 = 0.96°≈1°Ans.(2)

From (10):

    Δq = (4f.sup.2 /a) Δα = [4(50).sup.2 /67].sup.. 0.96 (π/180)  ≈ 2.5 mm                              Ans. (3)

EXAMPLE 2

In FIG. 5, dial 38 turns through 360° to rotate the second horizontaldeflector 8 through Δα= 1° to bring the convergence from ∞ to 1m. At thesame time the dial 37 is turned through 360° to adjust the angle Δβthrough 45° for sharp imaging on the film plane. Find the constant k:

From (12):

    k = Δβ/Δα

    k = 45/1 = 45

Answer to Example No. 2

From (5), (9) and (12):

    α = k.sub.2 /p                                       (13)

    β= k.sub.3 /p                                         (14)

    (dp/dt) = V                                                (15)

    ω.sub.c = rpm.sub.c = (dα/dt) = -(k.sub.2 /p.sup.2) (dp/dt)= -k.sub.2 V/p.sup.2                                        (16)

    ω.sub.f = rpm.sub.f =(dβ/dt) = -(k.sub.3 /p.sup.2) (dp/dt) = -k.sub.3 V/p.sup.2                                        (17)

From (16) and (17):

    (ω.sub.c /ω.sub.f)= (rpm.sub.c /rpm.sub.f) = (k.sub.2 /k.sub.3) = k.sub.4                                                 (18)

Integrating (15) and evaluating the constant of integration:

    p = p.sub.o ± Vt                                        (19)

Referring to FIG. 5, dial 44 sets the estimated speed ±V of the objecttoward or away from the camera, and dial 47 sets the approximatedistance p_(o) of the object from the camera. Dial 47 turns with time.To start, set the dial 47 at p_(o) and the dial 44 at ±V; then the dial47 will turn according to (19); thus, V and p_(o) are always under thecontrol of the cameraman.

For lenses 6 of different focal lengths, the angle γ between the opticalaxes Z₁ Z₁ ' and Z₂ Z₂ ', shown in FIG. 3, changes. The angle γ alsochanges as q, the distance of the image plane to the optical center ofthe lens changes, as the focal plane to the object being photographed inchanged, but this change is small. From FIG. 3:

    d.sub.1 = γq                                         (20)

    D.sub.2 = 65 z.sub.o                                       (21)

Hence:

    D.sub.2 = D.sub.1 z.sub.o /q                               (22)

From (2) and (22):

    D.sub.2 = (D.sub.1 Z.sub.o /f)(1-f/p)                      (23)

    Since f ˜ 50mm and 1000 <p<∞; 0.04 <f/p <0

    32mm < f < 100mm

    D.sub.1 = 9.8mm

    z.sub.o ≈ 100.sub.mm

Hence:

    30 ≲ D.sub.1 z.sub.o /f)≲ 10               (24)

For a 50mm lens γ is computed:

    γ = 9.8/50 ≈ 0.2 radians

    γ= 0.2 ≦ 57.2 ≈ 11.4°          (25)

The conclusion is that D₂ varies a maximum of 4% from ∞ to 1 meter andhence may be held constant without troublesome vertical image parallax.However, in changing lenses from 30 to 100mm focal lengths the anglewill change by a factor ˜3; and provision must be made to vary D₂.

The calculation for D₂ is made for an air path. Since most of thedistance travelled by the light ray along the axis Z₂ Z₂ ' is in glasshaving an index of refraction n, the angle γ is decreased to ≈γ/n and D₂to ≈D₂ /n.

Referring to FIG. 7, there is diagrammatically shown a plan view of the3-dimensional camera of this invention which includes a binocularviewfinder 4. The rays reflected by the rotating shutter 1 in thedirection FG are imaged upon a third mutually extinguishing filter setand reticle 19 and diffusion screen 15 at the image plane shown in FIG.6. A rear view projection or diffusion screen 15 makes the projectedimages visible in the viewfinder. Thee third mutually extinguishingpolarized filter set and reticle 19 is similar to the second mutuallyextinguishing filter set 30 at the gate 2, except that it has inscribedhorizontal reticle lines 23, 24 and vertical reticle lines 26, 27, etc.The binocular viewfinder 4 comprises binocular inverting eyepieces 53and 54 in front of the cameraman's eyes, 55 and 56. Polarizers 57 and 58are respectively polarized horizontally and vertically so that the righteye 56 sees only the imagme appearing on area 20 and the left eye 55sees only the image appearing on the area 21. The two images are broughtinto vertical alignment by prisms 59 and 60. Thus, with this binocularviewer, the cameraman reconstructs a 3-dimensional image as it isphotographed by the camera, and as it will be seen when projected on ascreen. The 3-dimensional binocular viewer shown in FIG. 7 may beemployed in other applications. For example, in the editing of3-dimensional motion picture film, it is necessary for the editor to seethe images in 3-D. This may be accomplished by inserting a polarizingfilter such as is shown in FIG. 4 over the pair of images on the film inthe gate of the Moviola device, and utilizing the binocular viewingdevice just described; whereby the motion picture images will besuperimposed and fused into a 3-dimensional image by the editor.

It is within the purview of the present invention to vary theinterocular distance a. An increase in the interocular distance a hasbeen employed in the prior art to increase the depth perception,particularly for distant scenes. In accordance with equation (10) thismay be accomplished by an increase or decrease in the constant factor ain this equation and a corresponding gear ratio change. To change a, thedistance between the horizontal deflectors 7 and 8 is varied. The firstand second horizontal deflectors may be mounted upon separate structureswhose distance from each other along the X axis may be controlled in anysuitable manner, as for example, a screw mechanism (not shown). Thehuman eyes have a fixed interocular distance a, and it is natural to see3-dimensional scenes in this manner. The present device operates in anentirely satisfactory manner with a fixed interocular distance a, whichmay be chosen at 67mm, the means interocular distance of the human eyes.However, for special applications, a means may be provided to vary theinterocular distance a.

There is thus provided a 3-dimensional camera device which enables themotion picture photography of stereo image pairs with a relativelysimple device. With this device, the cameraman views the stereo pairs asthey are photographed onto single frames of a single film strip whilesimultaneously or independently controlling the convergence and focus,and moving objects may be "tracked" under control of the cameraman. Inthis manner, 3-dimensional effects are obtained which increase the depthperception of the projected images by the viewer while enhancing theirrealism and dramatic impact.

In another embodiment of this invention, mutually extinguishingpolarizers are mounted with their polarizing axes mutually at 90° andrespectively at ± 45° to the horizontal. A first set of such filters maybe placed between the lens 6 and the first and second positions; asecond set of such filters at the film gate 2; and a third set of suchfilters at the diffusion screen 15 at the image plane of the viewfinder.Referring to the first set of filters in front of the lens 6, there isone polarizer in the half plane above the lens axis Z Z', and the otherpolarizer in the half plane below the optical axis Z Z'. An advantage ofutilizing the ± 45° directions is that the right and left imageintensities are more nearly balanced, and the depolarizer, quarter orhalf wave plates may be eliminated. Further, strain in the glass opticalelements will not detract from the blocking effect of the first andsecond sets of mutually extinguishing filters. With the polarizing axesat ± 45° for mutually extinguishing filters, the reflection from apolished metal surface; that is a half silvered surface or thereflecting surface of the shutter of a reflex camera, introduces arotation of the planes of polarization by 90°. As a consequence, toprovide extinction, the third set of mutually extinguishing filters 19at the at the diffusion screen 15 at the image plane of the viewfinderhas its planes of polarization turned through 90° relative to the secondset of mutually extinguishing polarizers at the gate and the polarizers28 and 29 are both at +45°; after reflection from a half silvered planethe light from DE is rotated through 90°. In other respects with the ±45° polarizers, this system functions as previously described.

In the embodiments described herein, the R R' axis is displaced by theinterocular distance a to the right of the lens axis Z Z', and the L L'axis is approximately in line with Z Z'. In an alternate embodiment, theL L' axis may be displaced to the left and R R' may be approximately inline with Z Z'.

A 3-dimensional camera device according to this invention which utilizesa half silvered cube as the second horizontal deflector requires about 3stops additional opening on the camera lens since two parallel efficientpolarizers transmit 33 to 40% light and the half silvered horizontaldeflector cube reflects and transmits about 45% of the light; otherlosses in the system being small with nonreflecting surfaces on theoptical elements. However, when the second horizontal reflector is atotal internal reflecting prism in the lower half plane, no light islost upon total internal reflection, and about 1.7 stops are required.

In another modification, achromatic prisms 11 and 12 may be combinedwith the first horizontal deflector and the first vertical deflector,respectively, rather than as the separate elements shown herein. Variousother embodiments may be made by those skilled in the art which willfall within the scope of this specification and appended claims.

Have thus described the invention, what I wish to claim is:
 1. In a3-dimensional camera device for photographing an object space in 3dimensions, a first aperture and a second aperture separated by aninterocular distance, which respectively receive first and second lightray bundles from said object space, a monocular lens having a firstoptical axis and a second optical axis passing through the opticalcenter of said lens, a film gate, a film frame at said film gate, afirst aperture first deflector, and a first aperture second deflector,to deflect the said first light ray bundle from the said first aperturealong said first optical axis, a second aperture first deflector and asecond aperture second deflector to deflect the second light ray bundlefrom said second aperture along said second optical axis, a first set ofmutually extinguishing filters located between the said lens and saidfirst and second apertures, a second set of mutually extinguishingfilters located at said film gate dividing said film gate into a firstarea coinciding with the plane of the image of the object space carriedby the first light ray bundle, and a second area coinciding with theplane of the image of the object space carried by the second light raybundle, said first area and said second areas being adjacent at the saidfilm gate, said first optical axis passing through center of said firstarea and the optical center of said lens, and said second optical axispassing through the center of the said second area and the opticalcenter of said lens, said first and second sets of mutuallyextinguishing filters causing said first light ray bundle to betransmitted only to said first area and to be excluded from said secondarea, and causing said second light ray bundle to be transmitted only tosaid second area and to be excluded from said first area.
 2. In a3-dimensional camera device according to claim 1, means to control theconvergence angle of the first and second light ray bundles from thesaid object space.
 3. In a 3-dimensional camera device according toclaim 1, means to control the position of the said lens along its axis.4. In a 3-dimensional camera device according to claim 1, means tocontrol the convergence angle of the first and second light ray bundlesfrom the said object space, and means to control the position of thesaid lens along its axis.
 5. A 3-dimensional camera device according toclaim 1, in which said camera is a reflex camera containing aviewfinder, a third set of mutually extinguishing filters, said thirdset of mutually extinguishing filters being located at the image planeof said viewfinder.
 6. A 3-dimensional camera device according to claim5, in which said viewfinder is monocular and said third set of mutuallyextinguishing filters divides the image plane into first and secondareas at the image plane of said viewfinder identical with said firstand second areas of film frame in said gate, the images seen in the saidviewfinder being identical with the images photographed on said filmframe.
 7. A 3-dimensional camera device according to claim 5, in whichsaid viewfinder is binocular, a pair of oculars, a fourth set ofmutually extinguishing filters on said oculars, prisms on said oculars,whereby said first and second images appearing at the image plane ofsaid viewfinder are overlapped and appear in 3 dimensions when viewedthrough said binocular device.
 8. A 3-dimensional camera deviceaccording to claim 5 in which horizontal and vertical reticle lines areplaced at the focal plane of said viewfinder, a calibrated scale to showconvergence distance p on said reticle, the displacement Δ₁ ofcorresponding points of the right and left images measuring saidconvergence distance p.
 9. A 3-dimensional camera device according toclaim 1, in which the said mutually extinguishing filters are polarizingfilters with their polarizing axes at right angles.
 10. A 3-dimensionalcamera device according to claim 9, in which the polarizing axes of thesaid polarizing filters are respectively in the horizontal and verticalplanes.
 11. A 3-dimensional camera device according to claim 8, in whicha half-wave retardation filter is located between one of the polarizingfilters and the object being photographed.
 12. A 3-dimensional cameradevice according to claim 8, in which a depolarizing optical element islocated between each of the said plarizing filters and the object beingphotographed.
 13. A 3-dimensional camera device according to claim 1, inwhich the mutually extinguishing filters are polarizers, the polarizingaxes of which are ±45° to the horizontal.
 14. A 3-dimensional cameradevice according to claim 1, a reversible adjustable speed motor, aspeed control device connected to said motor, a gear train driven bysaid motor, said gear train having first and second output shafts whosespeeds are proportional and at a controlled ratio to each other, a firstcoupling device and a second coupling device attached to said first andsecond output shafts respectively whereby the angle α through which atleast one of said horizontal deflectors is rotated, and the distance qof the optical center of the said lens to said film plane is varied indirect ratio to control the simultaneous convergence and focus whiletracking an object being photographed as said object moves toward oraway from the said camera.
 15. A 3-dimensional camera device accordingto claim 1, first and second achromatic prisms at first and secondapertures respectively to converge said first and second light raybundles.
 16. A 3-dimensional camera device according to claim 1, firstand second achromatic prisms at first and second apertures respectivelyto converge the said first and second light ray bundles, said first andsecond achromatic prisms each having a deviation of about 5°.
 17. In a3-dimensional camera device according to claim 1, a dark bar at the saidfilm gate separating the said frist and second area.
 18. In a3-dimensional camera device according to claim 1, a reflex camera havinga viewfinder, a first set of mutually extinguishing filters locatedbetween the said lens and said first and second apertures, a second setof mutually extinguishing filters located in proximity to the film planeat the gate, and a third set of mutually extinguishing filters inproximity to the focal plane of the viewfinder; a dark bar between saidfirst and second areas in the film gate, and a dark bar between thefirst and second areas at the focal plane of the viewfinder.
 19. In a3-dimensional camera device for photographing an object space in 3dimensions from a first aperture and a second aperture separated by aninterocular distance which respectively receive first and second lightray bundles from said object space, a monocula lens having a firstoptical axis and a second optical axis passing through the opticalcenter of said lens, a film gate, a film gate, a fixed first horizontaldeflector, and a rotable second horizontal deflector to horizontallydeflect the said first light ray bundle from the said first aperture bythe interocular distance to the said rotable second horizontal deflectoralong said first optical axis, first and second vertical deflectors tovertically deflect the said second light ray bundle from said secondaperture along said second optical axis, a first set of mutuallyextinguishing filters located along the paths of said first and secondlight ray bundles between said lens and said first and second apertures,a second set of mutually extinguishing filters located at said film gatedividing said film gate into an upper first area coinciding with theplane of the image of the object space carried by the said first lightray bundle, and a lower second area to coincide with the plane of theimage of the object space carried by the said second light ray bundle,said first optical axis passing through center of said first area andthe optical center of said lens, and said second optical axis passingthrough the center of the said second area and the optical center ofsaid lens, said first and second sets of mutually extinguishing filterscausing the said first light ray bundle to be transmitted only to saidfirst area and to be excluded from said second area, and causing thesaid second light ray bundle to be transmitted only to said second areaand to be excluded from the said first area, means to rotate said secondhorizontal deflector to control the convergence angle of the said firstand said second light ray bundles from the said object space, and meansto control the position of the said lens along its axis, whereby thesaid first and second light ray bundles are imaged respectively at thesaid first and said second areas, respectively, on the film frame in thesaid gate.
 20. A 3-dimensional camera device according to claim 19 inwhich the said second horizontal deflector is a rotable beam splittercomprising a transparent cube having a half-silvered diagonal plane. 21.A 3-dimensional camera device according to claim 19 in which the saidsecond horizontal deflector comprises a rotable totally reflecting prismpositioned in the lower half plane of the said lens and a transparentblock positioned in the upper half plane of the said lens.
 22. A3-dimensional camera device according to claim 19, means for adjustingat least one of said first and second vertical deflectors to control thevertical displacement and direction of the said second light ray bundle.23. A 3-dimensional camera device according to claim 19, said camerabeing a reflex camera, a first set of mutually extingushing filterslocated between said lens and said first and second apertures, a secondset of mutually extinguishing filters located in proximity to the filmplane at the gate, and a third set of mutually extingushing filterslocated in proximity to the focal plane of the viewfinder; dark barsbetween said images in the film gate and at the focal plane of theviewfinder, adjusting means for at least one of said vertical deflectorswhereby the said images on said first and second areas are adjusted forvertical position, and vertical parallax.
 24. A 3-dimensional cameradevice according to claim 19, in which the said second horizontaldeflector is mounted upon a vertical shaft, a first means to control theangle through which said shaft is turned; and second means for adjustingthe distance between the optical center of said lens and said filmplane.
 25. A 3-dimensional camera device according to claim 19, saidcamera being a reflex camera, a first mutually extinguishing filter setlocated between the lens and said first and second apertures, a secondmutually extingushing filter set located in proximity to film plane atthe gate, a viewfinder on said camera, a focal plane on said viewfinder,a third mutually extinguishing filter set located in proximity to thefocal plane of the said viewfinder; whereby right and left images appearin said viewfinder as they will photograph on the film, dark barsbetween said first and second areas at the film gate and correspondingfirst and second areas at the said focal plane of the viewfinder, saidtwo images being displaced horizontally and the convergence anglebetween said first and second light ray bundles being varied by arotation of the said second horizontal deflector.
 26. A 3-dimensionalcamera device according to claim 19 in which the said second horizontaldeflector is rotable, and in which said first means rotates saiddeflector about a vertical axis through an angle α to adjust theconvergence angle θ of the left and right images; and in which the saidsecond means moves the lens along its axis varying the distance qbetween the optical center of said lens and said film plane, couplingbetween said first and second means providng a motion through a distanceΔq proportional to the change in angle Δα of rotation of the said secondhorizontal deflector.
 27. A 3-dimensional camera device according toclaim 26, a differential to control the relative angle between the firstand second output shafts.
 28. A 3-dimensional camera device according toclaim 26, a means for decoupling the said coupling device, and a meansto independently control the angle of each of said shafts.